UK Clinical Trial Transparency Changes for Phase I Studies: What Sponsors Need to Know

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Clinical trial transparency continues to evolve across global regulatory environments. As part of wider changes to the UK’s clinical trial framework, new requirements affecting the registration and disclosure of Phase I healthy volunteer studies have drawn increased attention from sponsors and CROs alike.

As part of the wider UK clinical trial regulatory updates that came into force on 28 April 2026, the MHRA and HRA introduced new provisions affecting the registration and disclosure of Phase I Clinical Trials of Investigational Medicinal Products (CTIMPs) involving healthy volunteers. One notable change is the availability of automatic registration deferrals, which provide greater flexibility for commercially sensitive early-phase studies while maintaining overarching transparency obligations.

Understanding what has changed, what remains mandatory, and how to maintain compliance is essential for sponsors planning UK-based Phase I studies.

Why the Requirements Changed

Clinical trial transparency has become an important focus for regulators, patients, and the research community. At the same time, sponsors conducting First-in-Human and other early Phase I studies often face concerns around protecting confidential scientific and commercial information.

The UK’s updated clinical trial framework seeks to balance these competing priorities by introducing an automatic deferral mechanism for qualifying Phase I healthy volunteer studies rather than requesting one in the clinical trial application. Rather than requiring full public disclosure shortly after trial approval, sponsors may delay publication of detailed trial information to 30 months after the end of trial is declared while still maintaining a baseline level of transparency.

Which Studies Are Affected?

The automatic deferral applies to Phase I CTIMPs involving only healthy volunteers that receive combined approval from both the MHRA and a Research Ethics Committee (REC) under the updated requirements. Sponsors are no longer required to publish a full trial registration record immediately for these studies.

However, an automatic deferral does not mean sponsors are exempt from registration obligations.

What Sponsors Must Still Do

Even when a deferral applies, sponsors are required to publish a minimal trial record on a publicly accessible registry within 90 calendar days of receiving combined MHRA and REC approval and before the first participant is recruited into the trial.

For many sponsors, the preferred registry may be the ISRCTN Registry, which supports publication of the required minimal information and provides a registration number that can be shared with the regulators.

The minimal record must include information such as:

• Registry number
• IRAS ID
• Sponsor information
• Chief Investigator details
• REC decision and date
• General description of the study
• Trial start and end dates
• Recruitment start and end dates
• Justification for the deferral

These requirements ensure that the existence of the study remains publicly visible while allowing sponsors to defer disclosure of more detailed information to a later date.

What Can Be Deferred?

Sponsors using the automatic deferral may postpone several activities that would otherwise be required under standard transparency rules.

Specifically, sponsors are not required to (unless a deferral extension is requested for commercially confidential reasons):

• Register the trial in full until 30 months after the trial has ended
• Publish summary study results until 30 months after the trial has ended
• Offer study results to participants during the deferral period

These allowances can be particularly valuable for organizations developing novel therapies, platform technologies, or other programs where early disclosure could create competitive challenges.

The Deferral Is Optional

One important aspect of the new framework is that the automatic deferral is not mandatory.

Sponsors may choose to disclose information earlier than required if it aligns with their transparency strategy, corporate policies, investor expectations, or broader stakeholder engagement goals. The regulators explicitly allows sponsors to register studies, publish results, or provide findings to participants during the deferral period if they wish to do so.

As a result, sponsors should evaluate the benefits and risks of using the deferral on a study-by-study basis rather than treating it as a default approach.

Strategic Considerations for Sponsors

The new rules provide welcome flexibility, but they also introduce additional planning considerations.

Sponsors should assess:

• Registration Strategy Early: Clinical operations, regulatory, and transparency teams should determine during study start-up whether a trial qualifies for the automatic deferral and which registry will be used.
• Timing Requirements: Although full registration can be deferred, the 90-day deadline for publishing a minimal record remains firm. Missing this requirement could create compliance risks and delay trial activities.
• Long-Term Transparency Obligations: The deferral postpones disclosure requirements rather than eliminating them. Sponsors should establish processes for tracking future obligations, including full registration and summary results publication.
• Participant Communication: Even where formal results-sharing requirements are delayed, sponsors should still consider how they will communicate with participants and maintain public trust throughout the development process.

Looking Ahead

The UK’s updated approach reflects a growing recognition that transparency and innovation do not have to be mutually exclusive. For sponsors conducting Phase I healthy volunteer studies, the automatic deferral provides an opportunity to protect commercially sensitive information while still meeting regulatory expectations for public disclosure.

However, compliance remains far from a “set it and forget it” exercise. Sponsors must ensure that registration timelines, minimal record requirements, and future publication obligations are embedded into their development plans from the outset.

As sponsors increasingly conduct studies across multiple jurisdictions, understanding how UK requirements fit within the broader European transparency landscape is becoming essential. Coordinated planning can help organizations meet local requirements while maintaining a consistent global disclosure strategy. MMS supports sponsors through dedicated regulatory and transparency experts across Europe and other key regions, helping ensure compliance throughout the development lifecycle.

Organizations that proactively align regulatory, operational, and transparency strategies will be best positioned to take advantage of the flexibility these changes offer while avoiding unnecessary compliance challenges.